Plant roots aid the growth and functions of several kinds of microorganisms such as plant growth-promoting rhizobacteria, mycorrhizal fungi, endophytic bacteria, actinomycetes, nematodes, protozoans which may impart significant impacts on plant health and growth. Plant soil–microbe interaction is an intricate, continuous, and dynamic process that occurs in a distinct zone known as the rhizosphere. Plants interact with these soil microbes in a variety of ways, including competitive, exploitative, neutral, commensal, and symbiotic relationships. Both plant and soil types were found to have an impact on the community diversity and structure of the rhizosphere, or vice versa. The diversity of microorganisms in soil is thought to be essential for the management of soil health and quality because it has different plant growth-promoting or biocontrol effects that could be very advantageous for the host plant and alter plant physiology and nutrition. The composition of microbial community is influenced by soil and plant type. Besides these beneficial microbes, the soil also harbors microorganisms that are detrimental to plants, competing for nutrients and space, and causing diseases. Numerous microorganisms have antagonistic activity and the ability to defend plants from soil-borne diseases. The study of the soil microbiome is essential for formulating strategies for transforming the rhizosphere to the benefit of the plants. This review pays special emphasis on the types of microbial populations in the soil and how they influence plant growth, nutrient acquisition, inter-relationships between soil microbes and plants, stress resistance, carbon sequestration, and phytoremediation.

This study aimed to increase the therapeutic potential of medicinal plants through inoculation with endophytic fungi. As endophytes influence medicinal plants’ biological properties, twenty fungal strains were isolated from the medicinal plant Ocimum tenuiflorum. Among all fungal isolates, the R2 strain showed the highest antagonistic activity towards plant pathogenic fungi Rosellinia necatrix and Fusarium oxysporum. The partial ITS region of the R2 strain was deposited in the GenBank nucleotide sequence databases under accession number ON652311 as Fusarium fujikuroi isolate R2 OS. To ascertain the impact of an endophytic fungus on the biological functions of medicinal plants, Stevia rebaudiana seeds were inoculated with Fusarium fujikuroi (ON652311). In the DPPH assay, the IC₅₀ value of the inoculated Stevia plant extracts (methanol, chloroform, and positive control) was 72.082 µg/mL, 85.78 µg/mL, and 18.86 µg/mL, respectively. In the FRAP assay, the IC₅₀ value of the inoculated Stevia extracts (methanol, chloroform extract, and positive control) was 97.064 µM Fe²⁺ equivalents, 117.662 µM Fe²⁺ equivalents, and 53.384 µM Fe²⁺ equivalents, respectively. In the extracts of the plant inoculated with endophytic fungus, rutin and syringic acid (polyphenols) concentrations were 20.8793 mg/L and 5.4389 mg/L, respectively, which were higher than in the control plant extracts. This approach can be further utilized for other medicinal plants to increase their phytochemical content and hence medicinal potential in a sustainable way.

Kumar A, Tapwal A. 2022. Diversity of arbuscular mycorrhizal fungi and root colonization in Polygonatum verticillatum. Nusantara Bioscience 14: 53-63. Diversity of arbuscular mycorrhizal fungi (AMF) associated with Polygonatum verticillatum (L.) All. was investigated in two sites of Himachal Himalaya, India. A total of 15 AMF species were isolated and identified from the rhizosphere soil of P. verticillatum. The spore density was 1.48 ± 1.91 and 3.99 ± 3.78 per 20 gram of rhizosphere soil at site-I and site-II, respectively. Mycorrhizal colonization in the roots of P. verticillatum was recorded 46.12 and 52.23 percent at site-I and site-II, respectively. The mycorrhizal structures like darkly stained endophytic hyphae, coiled intracellular hyphae, Y-shaped hyphae and ‘H’ connection (Arum type) were recorded.